Control means for electric motor operated devices



Oct. 24, 1933. c, s. PINKERTON CONTROL MEANS FOR ELECTRIC MOTOR OPERATEDDEVICES I 2 Sheets-Sheet 1 Filed Dec. 17, 1931 Oct. 24, 1933. 1,931,771

CONTROL MEANS F OR ELECTRIC MOTOR OPERATED DEVICES C. S. PINKERTON' 2Sheets-Sheet 2 Filed Dec. 17, 1951 3) MOW/v mam/wow Patented Oct. 24,1933 UNITED STATES PATENT OFFICE CONTROL lVIEANS FOR ELECTRIC MOTOROPERATED DEVICES Application December 17, 1931 Serial No. 581,576

13 Claims.

This invention relates to improvements in control means for electricmotor operated devices, and the invention more particularly relates toimprovements in remote pressure control means for fluid distributionsystems.

The remote pressure control means herein disclosed is in general of thecharacter described and claimed in my prior Patent No. 1,743,233, datedJanuary 14, 1930.

An object of the invention is to provide a novel system of relays forcontrol of an electric motor operated device.

Another object is to provide improved and simplified control means for arelay system of the character aforementioned.

Another object is to provide means enabling utilization of a minimumnumber of low voltage control lines between a flow controlling valve ofthe distribution system and a point in the system relatively far removedfrom said valve.

Another object is to provide means of the character aforementionedwherein certain of the control elements employed are operable withrelatively low current consumption, whereby relatively smalltransmission lines may be employed regardless of the distance between agiven remote point and said elements of the control system.

Another object is to provide means responsive to pressure conditions ata remote point in the fluid distribution system to directly control thepressure of fluid supplied to the latter.

Another object is to generally-improve the details of construction andoperation of the parts of the fluid pressure control system as a whole.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of theinvention which will now be described, it being understood that theinvention is susceptible of embodiment in other forms without departingfrom the scope of-the appended claims.

In the drawings, Figure 1 illustrates schematically and diagrammaticallya portion of a fluid distribution system having my improved controlmeans applied thereto, and

Fig. 2 is a similar illustration of my invention as applied to thecontrol of compressors and compressor-unloaders of a fluid distributionsystem for maintenance of a predetermined substantially constantpressure at a remote point in the latter.

Referring to Fig. 1, the numeral 5 designates a conduit through which afluid, such as gas, is

Interposed between conduits 5 and 6 isa valve 7 which may be of thewell-known oscillatable disk type,--a reversible motor 8 being providedfor driving said valve from an extreme open position to an extremeclosed position, and vice versa,.or to any intermediate position,through the medium of suitable worm and pinion gearing 9,-the worm shaft9 being threaded to effect travel of a nut 9 which in its respectiveextreme positions engages limit switches 9, 9 to effect interruption ofthe motor circuit connections. As will be understood the conduit 6 maybe of considerable length, say five or ten miles long, between the valve7 and a point 6 at which it is desired to maintain a substantiallyconstant fluid pressure of predetermined value.

Accordingly I provide at the point 6 a suitable pressure responsivedevice, such as the prover-bell designated in general by the numeral 10,said device as shown being provided with a pivoted contactor 11 which isretained in the intermediate or neutral position illustrated uponattainment and during maintenance of a predetermined pressure of fluidat the point 6 of conduit 6. Upon a predetermined decrease in pressureof the fluid at point 6 contactor 11 is movable upwardly by bell 10 intoengagement with a stationary contact 12, and upon a predeterminedincrease in pressure of said fluid the contactor 11 is moved downwardlyby bell 10 into engagement with a stationary contact 13,it beingunderstood that the device 10 is calibrated and/or adjustable to providefor response thereof in either sense in accordance with the requirementsof the particular installation. Also it is to be understood that anyother suitable form of pres- 1 sure responsive device may be employed ifdesired.

More particularly, assuming a given adjustment of valve 7 (say,half-open positioning thereof as indicated by the position of nut 9 andfurther assuming a demand or rate of consumption of the fluid such thatthe pressure thereof at point 6 remains of a substantially constantpredetermined value, there will of course be no movement of contactor 11to either 01. its extreme positions, and hence there will be nonecessity for adjustment of valve 7. On the other hand, if the rate ofsupply through valve 7 exceeds the rate of consumption of the fluid thepressure of the latter will be increased, with resultant movement ofcontactor 11 into engagement with contact 13. The arrangement ispreferably such that upon engagement of contactor 11 with contact13,-the contacts 14, 14 of switch 14 having previously been closed bydepression of push button 44 ,--a rectified current of relatively lowvoltage is caused to flow in a'g'iven direction through the operatingcoil 15 of a polarized relay 15 of well known form. The energizingcircuit for coil l5 may be traced from contactor 11 by conductor 16through said coil, by conductor 17 to and through contacts 14 14 ofswitch 14 by conductors 18 and 19 through the elements 20 of a rectifiersystem of well known form, and thence by conductor 21.to contact 131Said rectifier system preferably includes a second set of elements22,-and said elements 20, 22 have associated therewith the secondarywindings 20 22* of a transformer 23 the primary windings of which areshown at 23 and 23 The primary windings 23, 23 may be supplied from asuitable source of alternating current of relatively high voltage, say110 volts, as represented by lines 1 1", which voltage may be steppeddown through the medium of the secondary windings 20, 22" to arelatively low value, say 10 volts.

Polarized relay 15 is provided with a contactor 15 which is movable fromthe neutral position thereof as illustrated to selectively engage either7 of the stationary contacts 15 or 15; and assuming engagement ofcontactor 15 with contact 15 upon energization of the circuit of coil 15in the manner just described, an energizing circuit is completed for thewinding 2 1 of a relay 24 the normally open contacts 24, 24 of which areadapted when closed to energize the field 8* of motor 8 and to efifect aflow of current in one direction through the armature of said motor.

The energizing circuit for winding 24 may be traced from line L byconductors 24 25 and 26 through the contacts 27 and 28 of a suitabletiming device which provides for intermittent closure of said contacts,by conductors 29 and 30 through a normally closed push button switch 31,by conductor 32 through the contacts of limit switch 9, by conductor 33through said winding 24, thence to and through contact 15 and contactor15 of the polarized relay. and by conductor 34 to line L.

Upon closure of contacts 24*, 24 of relay 24 a circuit is completed formotor 8 to provide for operation thereof in one direction, said circuitextending from line L by conductors 24 25 and 35 through the fieldwinding 8", by conductors 36 and 37 through said contacts 24', byconductor 38 to and through the armature of said motor, by

conductor 39 through said contacts 24, and by conductors 40 and 41 toline L.

As will be understood the energizing circuit for the winding 24' ofrelay 24 will only be completed during closure of the contacts 27, 28 ofthe aforeto be understood that such timing device may and preferablydoes include adjustable elements of the character disclosed in my PatentNo. 1,743,233 whereby the periods of'opening and closing 0! contacts 27,28 may be preselected at will to predetermine the duration of eachintermittent operation of motor 8 and to permit a given adjust- :ment ofvalve 7 by motor 8 to become effective (with reference to the pressureof fluid at the point 6) prior toa repeated operation of said motor 8.

After the required degree of closing movement of valve 7 has beeneffected through one or more periods of intermittent operation of motor8 the pressure of fluid at the point 6 will be reduced to the desiredvalue, with consequent movement of contactor 11 out of engagement withcontact 13 to the neutral position illustrated,--thereby interruptingthe en'ergzing circuit of the polarized relay coil 15 to insure againstfurther automatic movement of valve 7 toward its fully closed 1position.

if the rate of consumption oi fluid from conduit 5 has decreased to avery low value, the contactor 11 may be retained in engagement withcontact 13 even after valve 7 has been moved to its fully closedposition. In this event, how ever, the contacts of limit switch 9 willbe opened automatically to interrupt the circuit of motor 8 wherebyinjury to the valve 7 or the driving elements thereof is prevented.

If the rate of consumption of fluid from conduit 6 exceeds the rate ofsupply thereof through valve7, the pressure of fluid at the remote point6 will of course be reduced, and upon a predetermined reduction ofpressure the contactor 11 will be caused to engage contact 12, with a'consequent flow of rectified current of relatively low voltage throughthe ml 15 of polarized relay 15, but in a reverse direction from thataforedescribed. Said circuit may be traced from contact 12 by conductor45 to and through the rectifier elements 22, conductors 46 and 18through contacts 14, 14 of switch 14, conductor 17 through said coil 15,and by conductor 16 to contactor 11. The consequent reversal of currentthrough coil 15 will cause engagement of polarized relay contactor 15with the contact 15 An energizing circuit will thus be completed for thewinding 46 of relay 46,said circuit extending from line L by conductors24 25 and 26 through contacts 27, 28 (when closed) of the timing device,by conductors 29 and 30 through the contacts of push button switch 31,conductors 32 and 47 through the contacts of limit switch 9, conductor58 through said winding 46 to and through said contact 15 and contactor15 and by conductor 34 to line L Contacts 46 and 46 of relay 46 areadapted when closed to complete an energizing circuit for motor 8 toprovide for operation of the latter in the reverse direction from thataforedescribed. Said circuit may be traced from line L by conductors 24,25 and 35 through the field winding 8, conductors 36 and 49 throughcontacts 46, by conductor 50 through the armature of motor 8, byconductor 38 through contacts 46", and by conductors 51 and 41 to lineL' During each period of closure of the contacts 46*, 46 of relay 46 (ascontrolled by the adjustment of the timing device representeddiagrammatically by the cam member 42), the motor 8 is operated in adirection to effect opening movement of valve 7,--which opening movementwill be continued intermittently in the manner aforedescribed until thefluid pressure at point 6 has been increased to the desired value, withconsequent disengagement of contactor 11 from contact 12 to de-energizethe polarized relay coil 15, or until valve 7 has been fully opened withre sultant opening of the contacts of limit switch 9 to interrupt thelast-mentioned circuit of motor 8.

vThe reference characters R and G designate electric signal lamps whichare respectively connected in circuit in parallel with the relaywindings 24 and 46 ,-said lamps being normally jointly illuminated uponclosure of the contacts 28, 27 of the timing device and extinguishedupon opening of said contacts (assuming operation of push button switch14 to effect disengagement of its contacts 14, 14

The lamp G is further subject to control by the contacts of limit switch9, so that upon full open positioning of valve '7 (as characterized byopening of the contacts of said limit switch 9) the-circuit of lamp Gwill be completely interrupted pending movement of valve 7 from its fullopen position. During such full open positioning of valve '7 the lamp Rwill be energized during intermittent closure of the contacts 28,

27 of the timing device, whereby a visual signal or indication of theposition of valve '7 is provided for the attendant. In like manner thelamp R is further subject to control by the contacts of limit switch 9so that upon full closed positioning of valve '7 the circuit of saidlamp will be interrupted by said limit switch contacts, and subsequentintermittent illumination of lamp G alone may be utilized to provide avisual signal or indication to the attendant that the valve 7 is in fullclosed position. In practice the lamp R is preferably colored red andthe lamp G is pref- I erably colored green.

' Also I preferably provide additional means affording an audible signalor indication to the attendant that the valve '7 is in its full openposition. Said means as shown may comprise an electrically operated bell52 the operating coil of which is adapted to be connected across lines LL upon closure of the contacts 53 53 of a relay 53. As shown relay 53 isprovided with a coil 53 which when energized tends to effect engagementof contact 53 with contact 53* Said relay is further provided with acoil 53 which acts when energized to withhold contact 53 from engagementof contact 53 against the biasing effect of coil 53. Coils 53, 53 arejointly energized and de-energized upon closing and opening,respectively, of the contacts 27, 28 of the timing device. Coil 53however, is additionally subjected to control by the contacts of limitswitch 9, so that upon full open positioning of valve '7 (withconsequent opening of the contacts of limit switch 9) the energizingcircuit of coil 53 will be interrupted to permit closure of contacts 5353 of relay 53 under the bias of coil 53 during each intermittentclosure of contacts 27, 28 of said timing device. The advantages of thisarrangement will be apparent to those skilled in the art.

It is to be understood that lines 1 1 may be connected to lines L Lrespectively, or to any other suitable source of alternating currentsupply.

Inasmuch as the conductors 16 and 18 are only required to carryrectified or direct current of relatively low voltage the dotted lineportions 16 and 18 thereof may be connected to a pair of telephone wiresor lines extending between the remote point 6 and the operating elementsof valve 7. By the means aforedescribed I have reduced, by one, thenumber of control lines required between the remote point and the flowcontrolling valve, as compared with the disclosure of my Patent No.1,743,233. This feature is of considerable importance since the rentalcharge for use of the telephone lines is thereby reduced by onethird. Iftelephone lines are not available for use in the manner hereincontemplated a relative saving of even greater amount but of likeproportion is effected in that only two control wires (instead of three)are required to be installed between said remote point and the valve '7.

In the foregoing description contacts 14 14 and 44 44 of switches 14 and44, respectively, were assumed to have been bridged or closed, suchclosure having been effected by merely depressing the push button 44. Ifit is desired to discontinue automatic control of valve '7, this may beeffected by merely depressing push button 44 to open the contacts 14 1444 44 Contacts 14, 14 are thus closed. as shown in the drawings, andcontrol of the operation of valve 7 is transferred from the contacts ofpolarized relay 15 to a pair of normally open push button switches 54and 55. Closure of push button switch 54 corresponds in function withclosure of contacts 15*, 15 of said polarized relay, whereby valve 7 maybe moved to the desired degree toward fully closed position; and pushbutton 55 may be temporarily depressed manually to effect the desireddegree of movement of valve '7 toward fully opened position. The visualand audible signal elements R, G and 52 function as aforedescribeclunder conditions of manual control of operation of valve 7. The relays24 and 46 are preferably provided with mechanical interlocking means ofwell known form (not shown) to insure against I simultaneous closure ofthe contacts thereof in the I event of simultaneous closure of the pushbutton switches 54, 55.

The fluid distribution system illustrated in Fig. 2 is in general quitesimilar to that shown in Fig. 1, and corresponding parts have beendesignated by like characters of reference in the two figures. Thus Ihave shown means identical with the elements aforedescribed to controlener gization of the coil 15 of polarized relay 15,- the contactor 15and contact 15 of said relay being adapted to control energization ofthe winding 24 of relay 24, and the contactor 15 and contact 15 of saidpolarized relay being adapted to control energization of the winding 46of relay 46. The contacts 24 and 46 of relays 24 and 46 in this instanceare respectively adapted to provide maintaining circuits for thewindings 24 46 of the latter under certain conditions, as hereinafterdescribed. The contacts 24 and 46 of said relays are adapted when closedselectively to provide energizing circuits for the split field windings56 or 56 of a motor 56 to effect operation of the latter in reversedirections selectively.

The driving motor 43 for the timing device 42 is subject to control bypush button switch 44, as in the previous illustration. In this case,however, I have shown the contacts 2'7, 28 of the timing device directlyinterposed between the supply line L and contactor 15 of the polarizedrelay. Motor 56 as shown is adapted to drive a worm 57 which meshes witha pinion 58 fixed to a shaft 58*. Fixed to one end of shaft 58 is acontactor 59 which is movable by said shaft throughout a predeterminedrange to sequentially engage and disengage a plurality of fixed contacts60, 61, 62, and 63,said contactor having a number of off positionsmarked 0, 1, 2, 3 and 4 wherein the elements function in the mannerhereinafter described.

Also secured to shaft 58- in angularly offset relation to each other area pair of contactors 65 and 66 which are adapted under given con ditionsto sequentially and'transiently engage the contacts 65, 66 respectively.Carried by con tactor 65 is a contactor 65 which is adapted to engage acontact 65 simultaneously with engage ment of contact 65* by saideontactor 65,- a well known form of lost motion connection beingprovided between contactors 65 and .65 .whereby the latter is permittedto disengage its cooperating contact 65 while the former remains inengagement with its cooperating contact 656. Also carried by contaetor66 is a eontactor 66 which is adapted to engage. a contact 66slmultaneously with engagement of contact 66 by said contaetor 66,--asimilar lost motion con nection being provided between contactors 66 and66 whereby the latter is permitted to disengage its cooperating contact66 while the former remains in engagement with contact 66, and alsowhile contactor 65 remains in engage ment with contact 66 asaforedcscribed.

Assuming closure of a push button switch 6?, the arrangement ispreferably such that upon closure of contacts 65 65 an energizingcircuit is completed for the closing coil 68 of an electromagneticallyoperable switch 66, the con-- tacts 68 of the latter when closedcompleting circuit for the motor 69 which is adapted. as shown to drivea compressor or pump '70 oi well known form. Compressor 76 is providedat one end thereof with a valve 'lll which is adapted to be opened uponenergization of the operating coil 70* to partially unload thecompressor where by the same delivers fluid at a rate of substan tiallyone-half of its capacity. As a'fcreindicatcd the coil '70 is energizedsimultaneously with completion of the circuit of motor 69, so that thecompressor 70 initially" delivers one-hall oi? its rated capacity Ifthis rate of supply of iiuid to conduit 6 is insufficient to restore thedesired degree of pressure at the remote point 6 the motor 56 willcontinue to operate to eventually effect disengagement of contactor 65from cooperating contact 65, thereby deenergizing the coil 70 to permitvalve 70 to functir a. in the normal manner, whereupon compressor 76operates at full capacity.

Thereafter if the pressure of fluid at the remote point 6 remains belowthe required value motor 56 will continue to operate to effect engagement of contactors 66 and 66 with their cooperating contacts 66 and66 ,--the contacts 66 66 completing an energizing circuit for theclosing coil '71 of an electromagnetically operable switch 71. Thecontacts 71 of switch 71 when closed complete circuit for the motor '72which drives a compressor 73 like the compares sor 70 aforedescribed.Compressor '73 is provided at one end thereof with a valve '73 which isadapted to be opened upon energization of the operating coil 73 topartially unload the compressor, said unloading efiect being providedprior to or at the instant when the compressor is started. Under theseconditions compressor 70 will be operating at full capacity andcompressor '13 at half-capacity. If the pressure at the remote point 6thereafter remains below the value desired or required motor 56 willcontinue to operate, with resultant disengagement of contacts 66, 66 tointerrupt the circuit of coil 73*, whereupon compressor 73 will likewiseoperate at full capacity.

It is to be understood that the timing device representeddiagrammatically by the cam 42 and contacts 28, 27 may be of'theadjustable character defined in my patent aforementioned, whereby theintermittent operations of motor are timed to permit eachjchange in therate of delivery from compressors 70 and/or '73 to take effect at theremote pointfi prior to a repeated operation ofsaid motor 56;

In order to more fully describe the operation of this system, let it beassumed that both of the compressoi's'w and {13 have been shut down(which condition would be represented by positioning of contactor '59 atthe point o l, with consequent disengagement oi. all of the contac tors65, 65 and '66, 66 from their associated contacts. Then if the pressureof fluid at the remote point 6 drops a predetermined degree be low therequired value contactor ll will engage contact 12 with consequentenergiaation of coil 15 of the polarized relay 15in a sense to 1 oengagement of contactor 16* with contact l5 ,-and assuming closure ofcontacts 2'2, 26 of the timing device at that instant, or within apredetermined period thereafter, circuit will be completed for the coil46 of relay i6,-said circuit being obvious. Contacts &6 when closedcomplete circuit for motor 56 through the field winding 56 of thelatter. Motor 66 will th upon operate in a direction to cause movemcontactor 59 from the position 0 'thereor rto engagement with segment66, and due to closure of contacts 46 oi relay 46 a maintaining circuitis provided for cell. 46* independently of he core tacts 2t", 28 oftiming device. Said r ing circuit may be traced from line U, byconductor T l through cell d6 to and through eon tacts i6 by conductor'16 to segment 66 and contactor 56, by conductor l6 through push buttonswitch 6'2 to line L Uperation of motor 56 in the required direction isthus insured pending movement of contaetor 56 out of engagement withsegment 66 and into the oil" position thereof designated by thenumeral 1. In the meantime. however, contactor 66 will have engagedcontact 65 to provide an energizing circuit for the coil 1'0 of theunloader valve of compressor 'lll,--said circuit extending from line Lby conductor 77 through coil ro by conductor '76 through con tact 65 andcontactor 65, and by conductors 79 and 76 through switch 6'? to line LContactor 65 will also be in engagement with contact 65 to complete acircuit for the coil 68 oi switch 68, said circuit extending from line Lby conductor 86 through coil by conductor 61 through contact 65,contaetor 65 and by conductors 79, 76 130 through switch 6? to line LUpon closure of contacts 66 01" switch 66 a circuit is completed formotor 69, and operation of thevpartially loaded compressor .70 isinitiated. After a predetermined period of time (dependent upon thedistance between remote point 6 and compressor '70) the pressure eiTectupon the fluid in conduit 6 of operation of the partially loadedcompressor will be transmitted to the point 6, and if the requiredpressure of fluid has been established eontactor 11 will be movedautomatically to its intermediate or neutral position to de-energize thecoil 15 of the polarized relay.

However, if the pressure of fluid at point 6 remains below the requiredvalue contactor 11 will remain in engagement with contact 12, and uponthe next period of closure of contacts 27, 28 of the timing device, theaforedescribed energizing circuit for coil 4L6 of relay 46 will be againcompleted, and upon movement of contactor 59 into 1,931,771 engagementwith segment 61 (through operation of motor 56 in the directionaforementioned) the aforedescribed circuit of coil 46 will be againmaintained pending movement of contactor 59 to the oif position marked2. At the same time contactor 65 will be moved out of engagement withcontact 65 to interrupt the aforedescribed circuit for coil '70 of theunloading valve. and thereafter compressor 70 will be operated at fullcapacity. The pressure effect of thisincrease in the rate of, supply offluid to conduit 6 by compressor '70 will be transmitted to point 6prior to the next period of closure of contacts 27, 28 of the timingdevice. If contactor 11 of the prover bell then remains in engagementwith contact 12, motor 56 is again operated in the same direction toeffect engagement of contactor 59 with segment 62, whereby theenergizing circuit of coil 46 is maintained pending movement ofcontactor 59 to the off position marked 3. At this time contactors 66and 66 will have been engaged with their cooperating contacts 66 and 66,to energize the coil '73 of the unloading valve '73 of the secondcompressor '73 and to energize the circuit of coil '71 of switch '71,whereby the contacts '71 of the latter are closed to complete circuitfor motor '7-2,with consequent initiation of operation of compressor 73in a partially loaded condition.

If after the aforementioned predetermined time interval the contactor 11remains in engagement with contact 12. closure of contacts 27, 28 willagain provide for energization of coil 46 of relay 46,-and contactor 59will cooperate with segment 63 to maintain said coil energized pendingmovement of contactor 59 to the off position marked 4. During suchmovement of contactor 59 contactor 66 will have been disengaged fromcontact 66, with consequent de-energization of coil 73*; ands thereafterthe compressor '73 (as well as compressor '70) will be operated at fullload. A suitable form of limit switch (not shown) may be provided toinsure against any further operation of motor 56 in the directionaforementioned,' after the contactor 59 has reached said off positionmarked 4.

. Assuming an increase in pressure beyond the value required at point 6(due, for instance, to

a decrease in rate of consumption of the fluid), contactor 11 of theprover bell will be caused to engage contact 13,--the coil 15 ofpolarized'relay 15 then being energized in a reverse sense reversedirection.

to cause engagement of contactor 15 with contact 15. Assuming closure ofcontacts 27, 28 of the timing device a circuit will be completed for thecoil 24 of relay 24.--said circuit extending from line L by conductors'74 and 82 through coil 24, thence through contact 15 and contactor 15through contacts 28, 27 to line L. Closure of contacts 24 of relay 24will complete a circuit for motor 56 through the field winding 56 of thelatter, with consequent operation thereof in the Thus contactor 59 willbe moved from off position 4 into engagement with segment 63 whereby theenergizing circuit of coil 24 is maintained pending movement ofcontactor 59 to its off position marked 3. In the meantime contactor 66will have been re-engaged with contact 66 to again energize coil '73,whereby compressor '73 will be partially unloaded. The step by stepoperations are repeated in a reverse order from that aforedescribed tothereafter disengage contactor 66' from contact 66 to entirely shut downthe compressor 73, to thereafter partially unload compressor '70, and tothereafter entirely shut down the latter as well; such automaticoperations depending of course upon the pressure of fluid at point 6.

By the provision of timing means of the character aforementioned thepressure change resulting from a given adjustment of the fluid flowcontrolling means is allowed to have full effect at the remote pointprior to the next succeeding adjustment. In this manner hunting of thefluid pressure control elements is substantially eliminated.

The control scheme of Fig.2 is particularly advantageous in that iteliminates the necessity for higher pressure of the fluid than isrequired at any point in the distribution system to maintain the desiredpressure at a remote point in the latter. For this reason leakage of thefluid (as an incident to excessive pressure thereof) is likewiseeliminated. 0n the other hand, the pressure of fluid at the remote pointis maintained substantially constant irrespective of variations in thedemand or rate of consumption at other points in the system or in thesystem as a whole.

While I have shown the compressors "70 and '73 as entirely controllingthe rate of supply of fluid to conduit 6, it will be apparent to thoseskilled in the art that I may lead from a source of supply of fluidunder given pressure a conduit which is connected to conduit 6 in arelation to normally by-pass said compressors,the normal pressure offluid and the rate of flow thereof through said auxiliary conduit beingpreferably such that the required pressure of fluid will be maintainedat a given remote point in the system under conditions of consumption offluid at an average or normal rate. With such an arrangement one or bothof the compressors would only be required to maintain the requiredpressure under "-peak load conditions in the distribution system. Also.of course, the aforementioned auxiliary conduit would preferably beprovided with a suitable form of check valve to avoid loss of theadditional pressures incident to operation of one or more of thecompressors.

It will be understood that visible and audible signaling elements of thecharacter illustrated in Fig. 1 may likewise be associated with thecontrol elements of Fig. 2; and in like manner suitable alternativemanual control elements may be added to the system of Fig. 2.

What I claim as new and desire to secure by Letters Patent is: I

1. In a fluid distribution system, in combination, a source of fluidsupply, a distribution conduit, and means for varying the rate of supplyof fluid to said conduit to maintain a substantially constant pressureat a remote point in-the latter under conditions of variation in therate of consumption of the fluid, said means comprising adjustable flowregulating means located adjaceht to the source of supply and switchingmecl': anism located at said remotepoint in the conduit and responsiveto high and/or low pressure conditions in the latter, power operatedmeans for effecting adjustment of said flow regulating means, and meansfor rendering said power operated means responsive to said switchingmechanism, said last mentioned means including a polarized relay, and asingle pair of conductors extending between said switching mechanism andthe coil of said polarized relay.

2. In a fluid distribution system, in combination, a source of fluidsupply, a distribution con duit, and means for varying the rate ofsupply of fluid to said conduit to maintain a substantially constantpressure at a remote point in the latter under conditions of variationin the rate of consumption of the fluid, said means comprisingadjustable flow regulating means located adjacent to the source ofsupply and switching mechanism located at said remote point in theconduit and responsive to high and/or low pressure conditions in thelatter, power operated means for effecting adjustment of said flowregulating means, and means for rendering said power operated meansresponsive to said switching mechanism, said last mentioned meansincluding a polarized relay, a single pair of conductors extendingbetween said switching mechanism and the coil of said polarized relay,and means operable independently of said polarized relay to render saidpower operated means ineil'ective for a given period preselected inaccordance with the distance between said flow regulating means and saidremote point in the conduit, whereby a given change in the rate of flowof fluid to said conduit is rendered effective at said remote pointprior to a repeated operation of said power operated means.

3. In a fluid distribution system, in combination, a source of fluidsupply, a distribution conduit, and means for varying the rate of supplyof fluid to said conduit to maintain a substantially constant pressureat a remote point in the latter under conditions of variation in therate of consumption of the fluid, said means comprising adjustable flowregulating means located adjacent to the source of supply and switchingmechanism located at said remote point in the conduit and responsive tohigh and/or low pressure conditions in the latter, power operated meansfor effecting adjustment of said flow regulating means, and means forrendering said power operated means responsive to said switchingmechanism, said last mentioned means including a polarized relay, asingle pair of conductors extending between said switching mechanism andthe coil of said polarized relay, means operable independently of saidpolarized relay to render said power operated means ineffective for agiven period preselected in accordance with the distance between saidflow regulating means and said remote point in the conduit, whereby agiven change in the rate of flow of fluid to said conduit is renderedeffective at said remote point prior to a repeated operation of saidpower operated means, and means for controlling operation of said poweroperated means independently of said switching mechanism and saidpolarized relay, said means comprising a transfer switch and a pair ofmanually operable push button switches, said push button switches beingoperable selectively to directly control the circuits normallycontrolled by said polarized relay.

4. In a fluid distribution system, in combination, a source of fluidsupply, a conduit, adjustable means located at a given point forcontrolling the flow of fluid to said conduit, power means for effectingadjustment of said adjustable means to increase or decrease the rate offlow of said fluid, and means operable automatically to control theoperation of said power means, said control means including a polarizedrelay coil located adjacent to said adjustable means, a pressureresponsive device associated with said conduit at a remote point in thelatter, said pressure responsive device including a movable contactorand a pair of stationary contacts to be mlectively engaged thereby,means for insuring a flow of current through said contactor in onedirection upon engagement thereof with one of said contacts and toinsure a reverse flow of current through said contactor upon engagementthereof with the other of said contacts, said last mentioned meansincluding a current rectifying device for each of said contacts, andmeans comprising a single pair of conductors extending between saidremote point and the terminals of said polarized relay coil, one of saidconductors being electrically connected to said contactor and the otherof said conductors being electrically connected to each of said currentrectifying devices. 5. In a fluid distribution system, in combination, asource of fluid supply, a distribution con duit, and means for varyingthe rate of supply of fluid to said conduit to maintain a substantial-1y constant pressure at a remote point in the latter under conditions ofvariation in the rate of consumption of the fluid, said means comprisinga power operated compressor located adjacent to the source of fluidsupply, switching mechanism located at said remote point in the conduitand responsive to high and/or low pressure con ditions in the latter,means controlled by said switching mechanism under predetermined lowpressure conditions to initiate operation of said compressor inpartially loaded condition, and means operable automatically after apredetermined time interval, in the event of continued low pressureconditions, to effect full load operation of said compressor.

6. In a fluid distribution system, in combination, a source of fluidsupply, a distribution conduit, and means for varying the rate of supplyof fluid to said conduit to maintain a substantially constant pressureat a remote point in the latter under conditions of variation in therate of consumption of the fluid, said means comprising a plurality ofpower operated compressors located adjacent to the source of fluidsupply and having the outlet ends thereof respectively connected withsaid conduit, switching mechanism located at said remote point in theconduit and responsive to high and/or low pressure conditions in thelatter, means controlled by said switching mechanism under predeterminedlow pressure conditions to effect partial unloading of one of saidcompressors and to initiate operation of said compressor in partiallyloaded condition, and associated means also controlled by said switchingmechanism and operable after a predetermined time interval to effectfull load operation of said compressor, said means also actingthereafter to partially unload another of said compressors and toinitiate operation of the latter in partially loaded condition, and saidmeans also acting thereafter to effect full load operation of saidsecond mentioned compressor.

7. In a fluid distribution system, in combina tion, a source of fluidsupply, a distribution conduit, and means for varying the rate of supplyof fluid to said conduit to maintain a substantially constant pressureat a remotepoint in the latter under conditions of variationin the rateof consumption of the fluid, said means comprising a plurality of poweroperated compressors located adjacent to the source of fluid supply andhaving the outlet ends thereof respectively connected with said conduit,switching mechanism located at said remote point in the conduit andresponsive to high and/or low pressure condil ke tions in the latter,means controlled by said I switching mechanism under predetermined lowpressure conditions to effect partial "unloading of one of saidcompressors and to initiate operation of said compressor in partiallyloaded condition, and associated means also controlled by said switchingmechanism and operable after a predetermined time interval to effectfull load operation of said compressor, said means also actingthereafter to partially unload another of said compressors and toinitiate operation of the latter in partially loaded condition. and saidmeans also acting thereafter to effect full load operation of saidsecond mentioned compressor, said means being likewise controlled' bysaid switching mechanism under high pressure conditions to reverse thecycle of operations of said compressors and their respective unloaders,whereby the rate of supply of fluid to said conduit is intermittentlydecreased by predetermined amounts as required pending shut-down of allof said compressors.

8. In a fluid distribution system, in combination, a source of fluidsupply, a distribution conduit, a plurality of power operatedcompressors interposed between said source of fluid supply and saidconduit, means for initiating operation of said compressors in sequence,associated means for insuring partial unloading of each of saidcompressors upon initiation of operation thereof and for thereafterefiecting full load operation of the latter, whereby the rate of flow offluid to said conduit may be increased in steps in accordance withvariations in demand for the fluid, said means comprising a drivingmotor for each of said compressors, means including a reversible pilotmotor and switch mechanism operable thereby to control energization ofsaid driving motors and to control unloading and loading of therespective compressors, a polarized relay operable to selectivelycontrol the direction of operation of said pilot motor, and a pressureresponsive switching mechanism located in said conduit at a point remotefrom said compressors, said last mentioned switching mechanism beingoperable to control energization of said polarized relay in accordancewith variations in pressure of fluid at said remote point with respectto a predetermined value.

9. In a fluid distribution system, in combination, a source of fluidsupply, a distribution conduit, a plurality of power operatedcompressors interposed between said source of fluid supply and saidconduit. means for initiating operation of said compressors in sequence,associated means for insuring partial unloading of each' of saidcompressors upon initiation of operation thereof and for thereaftereffecting full load operation of the latter, whereby the rate of flow offluid to said conduit may be increased in steps in accordance withvariations in demand for the fluid, said means comprising a drivingmotor for each of said compressors, means including a reversible pilotmotor and switch mechanism operable thereby to control energization ofsaid driving motors and to control unloading and loading of therespective compressors, a polarized relay operable to selectivelycontrol the direction of operation of said pilot motor, a pressureresponsive switching mechanism located in said conduit at a point remotefrom said compressors, said last mentioned switching mechanism beingoperable to control energization of said polarized relay in accordancewith variations in pressure of fluid at said'remote point with respectto a predetermined value, and means operable automatically andindependently of said polarized relay to render said pilot motorintermittently ineffective for predetermined periods of time, wherebythe pressure effect of a given change in the rate of supply of fluid bysaid compressors is transmitted to said remote pointprior to a furtherchange in said rate of supply.

10. A gas pressure-regulating system comprising in combination a'sourceof gas, a main for carrying the gas to a point remote from the source, avalve in said main at said source, a pressureresponsive diaphragm incommunication with the main at said remote point, a two-wire circuitextending from said source to said remote point, a source of directcurrent, a switch operatively connected to said diaphragm and arrangedto connect said source of direct current to said two-wire circuit whenthe gas pressure exceeds or drops below that to be maintained, so thatthe current sent over. said circuit is of one polarity when the gaspressure at the remote point is too low, and of the opposite polaritywhen the gas pressure is too high, a polarized relay connected in saidtwowire circuit at said source of gas, a control circuit located at saidsource of gas and having three legs, either of the first two legs beingarranged to be closed by the polarized relay, the third leg connected tothe first two and serving as a common return lead, a source of electriccurrent connected to a switch arm of said polarized relay and to thethird leg of said control circuit, two solenoids, each connected inseries with one of said first two legs, a switch in circuit with saidsolenoids, automatic means for alternately opening and closing saidswitch at regular time intervals, an electric motor operativelyconnected with said valve in the gas main, a power line for said motor,a motor-reversing switch connected between the motor and said powerline, said reversing switch arranged to be closed by one of saidsolenoids in the control circuit -to operate the motor to close saidvalve, and to be closed by the other of said solenoids to operate themotor to open said valve.

11. A gas pressure-regulating system comprising in combination a sourceof gas, a main for carrying the gas to a point remote from the source, avalve in said main at said source, a reversible electric motor arrangedto operate said valve, a pressure-responsive diaphragm in communicationwith said main at said remote point, a two-wire circuit extending fromsaid source to said remote point, a source of direct current, a switchoperatively connected to saiddiaphragm and arranged to connect saidsource of direct current to said pair of wires when the gas pressureexceeds or drops below that to be maintained so that the current sentover the pair of wires is of one polarity when the gas pressure is toolow, and of the opposite polarity when the pressure is too high, apolarized relay connected to the two-wire circuit at the source ofsupply, means controlled by said relay for causing said reversible motorto close or open said valve according to the polarity of the directcurrent flowing through said relay, means independent of said relaycontrol means constantly operating to interrupt the power to saidreversible motor at predetermined time intervals.

12. A gas pressure-regulating system comprising in combination a sourceof gas, a main for carrying the gas to a point remote from the source, avalve in said main at said source, a motor arranged to operate saidvalve in either direction, a pressure-responsive diaphragm in commu-'nication with said main at said remote point, a two-wire circuitextending from said source to said remote point, a source of directcurrent, a switch operatively connected to said diaphragm and arrangedto connect said source to said pair of wires when the gas pressureexceeds or drops below that to be maintained, so that the current sentover the pair of wires is of one polarity when p ing valve at saidsource, a reversible valve-actuating electric motor in a power circuit,a pressuremeasuring station remote from said gas source, two electricconductors connecting said gas source and station, two sources of directelectric current at said station arranged to establish a relay-actuatingcircuit in either direction in said conductors, a polarized relayoperatively connected to control the power circuit of said motor, saidrelay adapted to be actuated by the current in said relay circuit tocause said reversible motor to run in either direction according to thepolarity of the current, a gas-actuated diaphragm in communication withthe gas conduit system at said remote station, a switch operable by saiddiaphragm in one direction under increasing gas pressure and in theopposite direction under de creasing pressure, said switch arranged totransmit the current from either of said two sources of current to saidconductors, and.a constantlyoperating interrupter for the power circuitof said valve-actuating motor.

CLARENCE S. PINKERTON.

